The use of heat for the cauterization of bleeding wounds dates to ancient times. In the present century the use of radio frequency (RF) electrical current traveling through a portion of the body has been widely used to stop bleeding. Cauterization of tissue arises by virtue of its resistivity to RF energy. In the cauterization of blood, the proteins in it are heated to a temperature where the proteins congeal similar to the process involving the cooking of egg white. RF energy is preferred because its frequency is above that which could otherwise cause neuro-muscular stimulation. Several modes of RF cauterization of tissue are employed, such as monopolar or bipolar coagulation.
In monopolar coagulation, an active electrode of small dimensions such as of the order of one to two mm is applied to the bleeding site and the current path is completed through the body to a distal plate electrically in contact with a large surface area of the body such as the buttocks. One technique in which the monopolar mode may be employed involves fulguration which is the use of a spark or arc from the active electrode to the tissue. In bipolar coagulation, the two active electrodes are closely spaced, of the order of millimeters so that the current path is confined to a local region of the tissue.
Another technique for stopping bleeding involves the delivery of thermal energy, such as from a resistively heated probe as described in an article entitled "The Heater Probe: A New Endoscopic Method For Stopping Massive Gastrointestinal Bleeding" by David C. Auth et al and appearing in Vol. 74, No. 2, Part 1, pages 257-262 of Gastroentology, 1978. Laser energy has been suggested as described in an article entitled Endoscopic Laser Treatment by David C. Auth et al and appearing at pages 232-239 of the above Gastroentology publication.
A comparison of these various coagulating techniques appears at pages 362-366 of an article entitled "Nonsurgical Management Of Acute Nonvariceal Upper Gastrointestinal Bleeding" by David C. Auth et al and published at page 349 of Hemostasis and Thrombosis, Vol. 4, 1979, Edited by T. H. Spaet, published by Grune & Stratton, Inc. Thus, it is well known that tissue proteins coagulate at temperatures of 50.degree.-100.degree. C.
The coagulation of bleeding vessels such as in the case of bleeding ulcers in gastrointestinal parts of the body requires use of a long endoscope from the distal end of which the bleeding area first must be identified and subsequently treated with an instrument passed through a channel provided in the endoscope. The locating of the bleeding site is not easy since often the tissue wall being investigated may be moving, debris in the form of particles is likely to be present and interfere with vision and the blood flow itself tends to obscure the bleeding sources. These can be very small, of the order of less than a mm with many present in a particular area and each to be coagulated.
The endoscope, or the device put through it, therefore, is also provided with a wash channel through which a fluid such as a liquid or gas can be supplied to flush away the debris and permit visual scrutiny of the tissue area to be treated. In the above identified Endoscope Laser Treatment article, a flow of gas which is coaxial with the laser fiber is used to clear tissue. In a known electrosurgical device of the bipolar type, a pair of conductors are embedded in the wall of a catheter whose central bore is used to supply gas or liquid to the tissue area to be treated. The conductors project in the form of spaced-apart loops from a distal end of the catheter.
When a tissue area is to be treated, each tiny source of blood is subjected to heat treatment. This means the clearing of tissue with a wash of fluid, followed by the application of heat, again clearing the area and applying heat and so on until all of the bleeding areas have been coagulated. In such treatment, the repeated applications should be made with facility in an accurate manner with a minimum of undesirable side effects such as the sticking of the coagulating device to tissue areas. The laser technique has the advantage of not requiring physical contact, and thus avoiding such sticking problems, but because of the variable way in which different tissue conditions permit absorption of the laser energy, precise control during tissue treatment is difficult. The monopolar electrosurgical device tends to injure tissue not intended to be treated and even cause damage in the target area itself such as by excessively deep effects in the target area. Hence, bipolar electrosurgical treatment of tissue has been used and proposed as improving safety because the electric current is confined to the small area between electrodes. Several bipolar devices have been proposed.
For example, starting with an early 1875 U.S. Pat. No. 164,184 to Kidder, a bipolar electrosurgical device is proposed wherein a pair of conductors are spirally wound onto a rubber probe body in which the conductors are embedded. The conductors are shown terminated at a distal hemispherically shaped end of the probe body. A thermally heated knife is described and shown in the U.S. Pat. No. 1,366,756 to R. H. Wappler who employed a pair of half-round cross-sectionally shaped conductor rods twisted about an insulator to connect to a heater-knife. In 1934 Kimble proposed a bipolar electrosurgical device in U.S. Pat. No. 1,983,669 wherein a pair of conductors are shown twisted around a common insulator and project from a retainer body in a manner useful for side-wise or head-on application to a tissue area.
The U.S. Pat. No. 4,011,872 to Komiya proposes an electrosurgical device wherein, for example, as shown in FIGS. 5, 9 and 11, one conductor is connected to a high frequency energy source and is formed of three or four electrodes. The electrodes individually extend from a distal end with spacings between electrodes being variable to accommodate or grasp differently sized tissue areas. In the U.S. Pat. No. 3,987,795 to Morrison, an electrosurgical device is described to operate in a mode which is intermediate between the mono and bipolar modes of electrosurgery. This is achieved by mounting on one body, made of ceramic or glass, an active electrode and a return electrode whose surface area is made significantly larger than that of the active electrode. Various probe configurations are illustrated in the drawings.
Although these prior art electrosurgical devices are useful, they often do not provide satisfactory operation for a number of reasons. For instance, as previously noted, it is important that the probe body with which a cauterizing high frequency current is supplied can be repeatedly and precisely made to impinge upon the tiny blood vessel openings in the tissue area being treated independent of the orientation of the probe. This requires that as the probe is manually controlled at the proximal end of an endoscope, proper electrical contact is achieved to coagulate a blood vessel or other tissue target area whether the probe body is applied head-on, obliquely or side-wise to the tissue area.
Prior art devices such as taught by Kidder, Kimble and Komiya tend to cause hot points at the site being treated, thereby increasing a likelihood of a sticking of the probe body to the coagulated site. As the probe body is withdrawn from the coagulated site to which the probe is sticking bleeding may be restarted and the probe body requires recleaning so that the effectiveness of the entire procedure suffers.
Use of electrode configurations as shown or described in the above prior art, thus frequently is unsatisfactory because of the larger number of probe applications needed to treat a tissue target or achieve coagulation of a bleeding tissue area.